Re: New Beds in zone 8 -sand

In a message dated 98-01-20 13:28:10 EST, you write:

<<  a good soil has some of all these-though the organics are not needed by
the
 > plants.
 
 I beg to differ -- the organic matter is desperately needed by the
 plants for nutrients and to even more importantly to sustain the
 decomposition lifecycle to sustain earthworms, etc. which improve
 aeration.  While you can keep a *plant* alive with pure chemical salts,
 you cannot keep a soil alive in that manner.
 -- 
 Amy Moseley Rupp (amyr@austx.tandem.com)  Austin, TX, USDA z8b, Sunset z30 >>
Most soils in the world have very little organics in them.
some have a lot-like a peat bog or a tall grass prairia.
The organic compounds them selves have no effect on the plants except as to
what nutrients they may release over time as they decompose or in there
ability to " soften" up the soil. Of coarse all organics have come from purely
mineral sources and water and atmospheric gases. nitrogen CO2 and O2
What came first organics  in the soil of plants??


Particle size and composition are more important.
when rocks are weathered down they release chemicals that are bound to the
soil particles. Some soils hold onto these compounds harder than others. Since
not all rock formations have all chemicals in them some are better at growing
plants than others. tropical soils are famous for being very sterile. the rain
leaches away any free chemicals that the plants might use and other compounds
like aluminum are left to poison plants.


the best soils in the world are those that are made up of wind blown
particles.
 a black soil does not mean a good soil-- many clay soils are black because
all they are is organic clays .

Plants need only a few things to grow  light water atmospheric gases and some
nutrients from the soil. plants roots need O2 so a soil that is porous will
grow more and better roots. Organic compounds mixed into a soil do make the
soil more porous because as they brake down they leaves spaces. And they tend
to be oddly angled so that particles do not fit so closely together.

some of the most "dead" soils I have ever seem are organic soils-- just try to
grow most plants in pure peat.

In most soils the limiting factor for plant growth is nitrogen.  some plants
are better able to fix O2 from the atmosphere than others. When organic
compounds break down they free up nitrogen so that  other plants do not have
to work so hard to get it from the air.  It's the addition of free nitrogen
that makes the addition of organics great for soils. fertilizers have the draw
back that they are tied to a salt that over times builds up in the soil and
thus desiccates the plants tissue.


I hope you are not reading into my post that organics not good and should not
be add to the soil-because I am not--they are great. What I am saying is that
good soils need more than organics to be the best they can.
Organic soils are "alive" because of the bacteria and fungi  that feed on the
decomposing compounds they contain and many other animals and fungi feed on
the bacteria and  on the fungi living off the organic compounds. But this is a
different topic.
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